Asymmetric photoelectric effect: Auger-assisted hot hole photocurrents in transition metal dichalcogenides

Nanophotonics

article

Andrey Sushko¹  Alexander L. Efros²  C. Stephen Hellberg²  Hongkun Park¹  Philip Kim¹  Mikhail D. Lukin¹  Kristiaan De Greve¹  Madeleine Phillips²  Bernhard Urbaszek⁵  Andrew Y. Joe¹  Kenji Watanabe⁶  Takashi Taniguchi⁷ 

[1] Department of Physics, Harvard University;Naval Research Laboratory (NRL);Department of Chemistry and Chemical Biology, Harvard University;Currently at Imec;Université de Toulouse;Research Center for Functional Materials, National Institute for Materials Science;International Center for Materials Nanoarchitectonics, National Institute for Materials Science

关键词: Auger excitation;    2D materials;    optoelectronics;    transition metal dichalcogenides;   

DOI  :  10.1515/nanoph-2020-0397

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

Transition metal dichalcogenide (TMD) semiconductor heterostructures are actively explored as a new platform for quantum optoelectronic systems. Most state of the art devices make use of insulating hexagonal boron nitride (hBN) that acts as a wide-bandgap dielectric encapsulating layer that also provides an atomically smooth and clean interface that is paramount for proper device operation. We report the observation of large, through-hBN photocurrents that are generated upon optical excitation of hBN encapsulated MoSe 2 and WSe 2 monolayer devices. We attribute these effects to Auger recombination in the TMDs, in combination with an asymmetric band offset between the TMD and the hBN. We present experimental investigation of these effects and compare our observations with detailed, ab-initio modeling. Our observations have important implications for the design of optoelectronic devices based on encapsulated TMD devices. In systems where precise charge-state control is desired, the out-of-plane current path presents both a challenge and an opportunity for optical doping control. Since the current directly depends on Auger recombination, it can act as a local, direct probe of both the efficiency of the Auger process as well as its dependence on the local density of states in integrated devices.

【 授权许可】

CC BY